Answer
$3y^5+7y^5-2y^2-y^2=10y^5-3y^2$
Work Step by Step
Organise pairs of coefficients such that the coefficients will correspond to $10$ and $-3$.
$3y^\square+7y^\square-2y^\square-y^\square=10y^5-3y^2$
$3+7=10$
$-2-1=-3$. So
$3y^5+7y^5=10y^5$
$-2y^2-y^2=-3y^2$
$3y^5+7y^5-2y^2-y^2=10y^5-3y^2$.
